Drag wheels & Tires

[biminiLX]

Well after much waiting for various reasons my drag wheels and tires came in....AND they DON'T fit! Which is frustrating as I personally contacted the MFGR to confirm fitment along with the shop i ordered from also validated with them. So its obvious they didn't actually test fit them they just assumed they would fit based on brakes being smaller than gt350 in the rear. Anyway they hit the parking brake caliper. Determining what to do now. I really like these wheels and were the perfect price point for casual weekend racer.

Shouldn’t have to do this but a slight removal of materials (PC or metal or both ) to either the wheel and/or the brake should allow clearance based on pics.
But that can be difficult to access based on pics.
Good luck.
-J

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[NGOT8R]

With such a beautiful looking car, I suggest you remove the parking brake calipers, take them to a machine shop with a mill and have them shaved down. Then I’d mask off the entire caliper (except for the area that was milled down) and paint them. This will give you a clean and factory look.

 

[protraxduner]

I believe milling the caliper is only option for forgestar...which I can do myself...but that is not really and acceptable option from forgestar standpoint. Picture is deceiving I put 7.5mm spacer on and got 1mm clearance and wouldn't be comfortable driving and obviously would screw up offset. I am waiting for there solution until i dive into machining parking caliper.

 

[biminiLX]

Bummer on the spacer! If no spacer and just a caliper trim, I’d probably be inclined to do it, but I can tell you from personal experience, I bent 3” ARP studs using a 1/2 spacer and 18” DRs on my 2014.
Good luck and great looking car, I love the subtle paint mods and the front wheels.
-J

 

[protraxduner]

Well worked with forgestar and worked out a discount/refund if I tried and make the parking brake clear by clearancing it. I offered this up....assuming it was worth my time, because the next best option in wheels was another $800 or double. I had to remove most of the bolt flange and taper the outside caliper piece. Was not hard at all and once powdercoated will be oblivious to all but GT500 experts looking. Also didn't realize my steeda vertical links were touching rim barrel also so had to shave it some too. PLEASE remember this is a parking brake, so the material i removed and the shoulder i removed from the bolt will NOT be an issue, yeah i would rather not but it all worked out.

 

[NGOT8R]

There’s a workaround for everything. Sometimes we have to modify things that we shouldn’t have to, or would rather not, but at the end of all this, it looks like you’re back in business.

 

[protraxduner]

Few questions about tires and swapping out rears for drag racing. Does the GT500 care? I have OEM tire sensors mounted in the drag wheels/tires.

1. does it just figure it out and learn it has new wheels with new sensors on the back?
2. As related to tire diameter/circumference does the GT500 gripe when it sees F vs R bias? throw codes? And if it does is it just a code or does it limit speed/performance/other?

I have only drove it a few miles and it griped about pressure (they were little low) but obviously will be really low at drag strip. It appears it learned/picked up the new wheels/sensors no issue.

I just want make sure if the GT500 has an issue with tire size or sees a problem related to ABS functionality that it doesn't handicap my car at the drag strip. I have seen this on some GM cars.

thanks

 

[V00D00]

Few questions about tires and swapping out rears for drag racing. Does the GT500 care? I have OEM tire sensors mounted in the drag wheels/tires.

1. does it just figure it out and learn it has new wheels with new sensors on the back?
2. As related to tire diameter/circumference does the GT500 gripe when it sees F vs R bias? throw codes? And if it does is it just a code or does it limit speed/performance/other?

I have only drove it a few miles and it griped about pressure (they were little low) but obviously will be really low at drag strip. It appears it learned/picked up the new wheels/sensors no issue.

I just want make sure if the GT500 has an issue with tire size or sees a problem related to ABS functionality that it doesn't handicap my car at the drag strip. I have seen this on some GM cars.

thanks

low pressure wont hinder performance. on the latest tcm s/w changing tire size will, unless changed in the bcm module. I dont know the variance, only that on stock size calibration, the 325/35/18s work fine, but 305/45/18 do not and throw an ABS code. No idea if it hinders performance, but i suspect it does

 

[Jmeo]

The car has no idea what size tire is on it. Meaning, it's calibrated for stock size tires, and the car does not know if you changed to a different tire size. The only thing it knows is air pressure via the TPMS sensor. Changing tire size will not throw a code. If the TMPS sensors were not installed on the drag wheels, you will see the low air pressure icon on the dash, but it will not hinder performance.

The ABS sensor is in the knuckle, and it is looking for the axle to come to a stop, which then activates the ABS pulsing. It has nothing to do with what size tire is on the car.

 

[protraxduner]

The car has no idea what size tire is on it. Meaning, it's calibrated for stock size tires, and the car does not know if you changed to a different tire size. The only thing it knows is air pressure via the TPMS sensor. Changing tire size will not throw a code. If the TMPS sensors were not installed on the drag wheels, you will see the low air pressure icon on the dash, but it will not hinder performance.

The ABS sensor is in the knuckle, and it is looking for the axle to come to a stop, which then activates the ABS pulsing. It has nothing to do with what size tire is on the car.

I agree, I am good on air pressure, my concern is (in my case)...i am running a ~27" tire in rear and `28.5 tire in the front. Will this cause issues with ABS/traction control? If it is measuring speed/rotation/whatever then it will constantly be seeing that the front vs the rear is always off.....my question is will it matter and does it care and most importantly will it do something.

 

[V00D00]

The car has no idea what size tire is on it. Meaning, it's calibrated for stock size tires, and the car does not know if you changed to a different tire size. The only thing it knows is air pressure via the TPMS sensor. Changing tire size will not throw a code. If the TMPS sensors were not installed on the drag wheels, you will see the low air pressure icon on the dash, but it will not hinder performance.

The ABS sensor is in the knuckle, and it is looking for the axle to come to a stop, which then activates the ABS pulsing. It has nothing to do with what size tire is on the car.

yes it will. ABS light will come on, and SOTP calibration told me if felt different after luminated

 

[Jmeo]

I agree, I am good on air pressure, my concern is (in my case)...i am running a ~27" tire in rear and `28.5 tire in the front. Will this cause issues with ABS/traction control? If it is measuring speed/rotation/whatever then it will constantly be seeing that the front vs the rear is always off.....my question is will it matter and does it care and most importantly will it do something.

Steve has obviously seen some first hand issues that I have never seen, or heard of for that matter. Unless something has changed on this car -vs- my previous mustangs.....

My experience has taught me that (for my specific changes) the ABS has never activated for anything other than anti-lock issues, not wheel speed. Now, maybe I have never crossed that pre-programmed threshold by changing to such a dramatic tire size difference (from front to back), but I have never seen such an issue based solely on tire size change.

The PCM is programmed with the factory tire size. Perhaps you guys may want to use Forscan to adjust the tire size inside the BCM to keep the built in tire size range (if there is one) happy. This process would be a little more of a nuisance if you will be switching wheels on a street -vs- track basis, but it may be the only way to make the car happy.

In summary, perhaps there becomes an issue when the rear tire is smaller in diameter than the front? The BCM must see this due to rear wheel speed being faster than the front wheel speed? Typically the rear tire is taller (or the same size) than the front, as you know. Anyway, now I wanna know just to know, as I have not seen or heard of this issue before.

 

[protraxduner]

Here is the warning light i get after installing smaller rear tires. It doesn't come on until i have driven about 100ft. I can't tell any difference or feel any difference but have just been driving it back and forth to work.

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